A land-based system of radio navigation in common use over the continental United States and in its coastal waters. It was developed during World War II for the U.S. military. A civilian version, Loran-C, was developed in the 1950s. Loran-C can be used to determine position within about 30 ft (10 m) by comparing signals from multiple stations. Loran-like systems operate in many coastal waters around the world. However, the availability of the global positioning system (GPS), with a typical accuracy of 3 ft (1 m), has begun to relegate loran to backup status.